STONE, GREGORY W., Coastal Studies, Louisiana State University, Baton Rouge, LA 70803

Abstract: The Importance of Cyclogenesis on the Short-Term Evolution of Gulf Coast Barriers

Over the past several years, research has been conducted to determine the importance of cyclones on the morphodynamics and morphological maintenance of barrier islands along the northern Gulf of Mexico. Data are presented indicating the complexity and highly variable response of beaches to cold front passage across the northern Gulf, in addition to the impacts of tropical storms, hurricanes and winter storms in the Gulf of Mexico. A time series of net sediment flux for the subaerial mass and nearshore environments has been established for a 12 km stretch of the Northwest Florida coast and incorporates the morphological signature of six tropical storms/hurricanes and approximately 100 frontal passages. Three important conclusions have been reached based on these data: (1) barrier islands can conserve mass during catastrophic hurricanes (e.g., Hurricane Opal, a strong category 4 hurricane near landfall); (2) less severe hurricanes can promote rapid dune aggradation and contribute sediment to the entire barrier system; and (3) cold fronts play a critical role in the post-storm adjustment of the barrier by deflating the subaerial portion of the overwash terrace and eroding its marginal lobe. The data presented also indicate that barrier systems along the northern Gulf do not necessarily enter an immediate post-storm recovery phase, although nested in sediment-rich nearshore environments. It is anticipated that these findings will have implications for the longer-term evolution of barrier systems in mid latitude, microtidal settings elsewhere around the globe. 

AAPG Search and Discovery Article #90924©1999 GCAGS Annual Meeting Lafayette, Louisiana